Fluorinated compounds have been utilized as surface treating agents such as waiter/oil repellents. Articles having water/oil repellency or the like can be obtained by forming a coating film by applying the compounds on the surface of inorganic substrates (e.g. metals or glass) or resin substrates (e.g. polycarbonates). As such compounds, compounds having a perfluoroalkyl group and a (meth)acryloyloxy group (hereinafter referred to as a polymerizable group) have been known. As such compounds, for example, the following compound (1) may be mentioned (Non-Patent Document 1).CF3(CF2)7(CH2)2OC(O)CH═CH2  (1)
The compound (1) is applied on the surface of a substrate, followed by irradiation with ultraviolet rays or heat treatment, whereby a polymer is formed by the polymerization reaction of polymerizable groups. The polymer is withdrawn by hydroxy groups or other polar groups on the substrate, and perfluoroalkyl groups are arranged on the atmosphere side. As a result, a coating film formed by the compound (1) has water repellency.
However, it has been reported that the compound (1) is decomposed by the action of heat or an acid, and its decomposed product places a burden on the environment. Therefore, it is difficult to acquire the compound (1).
In recent years, as an alternative to the compound (1), the following compounds (2), (3) and (4) have been proposed. In the compound (3), s is an integer of from 8 to 13 and t is an integer of from 1 to 3. In the compound (4), u is an integer of from 1 to 200 (Patent Document 1, Non-Patent Document 1).CF3(CF2)5(CH2)2OC(O)C(CH3)═CH2  (2)CF3(CF2)2O(CF2CF2CF2O)s—(CF2)2(CH2)tOC(O)CH═CH2  (3)CF3O(CF2CF2O)uCF2CH2OC(O)C(CH3)═CH2  (4)
However, according to preconsideration by the present inventors, with the compound (2), as the number of carbon atoms in the perfluoroalkyl group moiety is small, the crystallinity is low, and no practically sufficient water/oil repellency and efficiency for removal of oil-and-fat stains can be obtained.
The compound (3) is difficult to prepare due to the structure of the (CF2CF2CF2O) moiety. For example, since it is difficult to control the molecular weight in its preparation, the molecular weight distribution of the formed product tends to be large, or a compound wherein the number of the unsaturated group is 0 or 2 will form in addition to the desired compound wherein the number is 1, and accordingly when the compound (3) is used as a surface treating agent as it is, problems may arise such that there is unevenness in the performance.
Since the compound (4) is highly hydrolysable, even if a coating film is once formed, it tends to be decomposed by the influences of an acid or an alkali, and its performance tends to be deteriorated. Particularly when it is used as a surface treating agent for glass containing an alkali component, its water/oil repellency tends to be deteriorated.